The electrically-conductive interconnect layers of modern integrated circuits are generally of very fine pitch and high density. A single, small defect in the precursor metal film which ultimately forms a metallic interconnect layer of an integrated circuit can be so positioned as to seriously damage the operational integrity of the integrated circuit.
Metal films of integrated circuits are typically formed by physical vapor deposition (PVD) or chemical vapor deposition (CVD). One PVD approach uses a DC magnetron apparatus such, for example, as the Endura® system available from Applied Materials Inc., located in Santa Clara, Calif. In a DC magnetron apparatus of the aforementioned type, ion bombardment of a metal or metal ahoy target causes atoms or molecules of the target material to be sputtered onto a substrates.
Although PVD systems can produce high quality metal films with relatively low defect densities, the inventors herein have observed that the degree of bit line miniaturization which can be achieved by such systems is determined, to a significant degree, by the resistivity of the metal films.